1. Field of the Invention
The present invention relates to a liquid discharge head and a method of manufacturing the liquid discharge head.
2. Description of the Related Art
FIG. 9 illustrates a diagram schematically illustrating a typical liquid discharge head which is used in an ink jet printing scheme. The liquid discharge head is provided with fine discharge ports 103 for discharging a liquid onto an Si substrate, flow paths 104 for connecting the discharge ports 103, and liquid discharge energy generating elements 101 which are provided on a part of the flow paths 104. On the Si substrate, a supply port 701 is formed which is connected to the flow paths 104. The liquid discharge head is manufactured by a method disclosed in U.S. Pat. No. 6,137,510, for example.
In Japanese Patent Application Laid-Open No. 2007-210242, there is disclosed a method of forming the supply ports in which guide holes are formed in the substrate by a laser process, and then a Silicon-crystal axis anisotropic etching is carried out so as to form the supply ports.
On the other hand, when it is assumed, as it is illustrated in FIG. 12, that the liquid discharge head includes independent supply ports 105 and the flow paths 104 which are connected to the discharge ports 103 and symmetrically disposed with respect to the energy generating elements 101, the following problems can be considered.
Here, the independent supply port represents a supply port which is independently connected to the flow path 104 connecting to the discharge port 103. In addition, a sub flow path represents a flow path in which the flow paths 104 are connected in two directions symmetrical to the discharge port 103. In addition, in a pillar-shaped Si (hereinafter, referred to as an Si pillar) 106 which is interposed between the independent supply ports, electric lines may be routed to the liquid discharge energy generating element.
Further, in this specification, a crystal orientation will be described using a Miller index. Surfaces which are crystallographically equivalent, for example, (100) and (010), are denoted as {100}. In addition, orientations which are crystallographically equivalent, for example, [100] and [010], are denoted as <100>.
In order to manufacture the independent supply port 105 of the liquid discharge head having a shape illustrated in FIG. 12, using a method described in Japanese Patent Application Laid-Open No. 2007-210242, the cross section of the supply port is formed in a rhombic shape in the vertical direction on the substrate surface. Even though the opening of the supply port can be formed to be small, when the independent supply ports are formed at high density, the width of the Si pillar between the two nearest supply ports becomes narrower, so that the strength of the head may be weakened. In addition, there may be a case where it is difficult to efficiently radiate toward the substrate the heat energy generated from the liquid discharge energy generating element, so that there is demand for improvements.
There is disclosed a case where after the guide holes are formed, the Si-crystal axis anisotropic etching is carried out and walls of the supply ports are formed on {110} plane. This is because a groove is easily formed in a <110> direction by the Si-crystal axis anisotropic etching with good accuracy for the purpose of forming a space which is a typical common liquid chamber (see FIG. 13). For this reason, the discharge ports of the liquid discharge head according to the related art are generally aligned in the <110> direction.
However, under a large number of conditions, it is known that the Si-crystal axis anisotropic etching rate of the {110} plane is faster than the etching rate of the {100} plane or the etching rate of the {111} plane which is another typical crystal orientation. For this reason, when the independent supply ports corresponding to the discharge ports aligned in the <110> direction according to the related art are formed along the <110> direction, there is a concern that the width of the Si pillar between the two nearest supply ports may be formed narrower than a desired width by the high etching rate to the <110> direction.